Britney Spears' Comeback Single Leaks Online

An exert of 'Womanizer', the first single to be taken from Britney Spears' new album, has appeared online.

A 40-second video clip appears to show Spears rehearsing the track in a Los Angeles dance studio along with her backing dancers.

Spears record label, Jive, who were keen to keep her comeback low key, are said to be considering legal action against the individual who published the video.

To combat any further leaks, extra security are understood to have been installed during the singer's rehearsal sessions.

As previously reported on Gigwise, Spears releases her new album 'Circus' on December 2nd, her 27th birthday.

The album is the follow-up to 2007's 'Blackout', which was well-received by critics but never performed live by the singer.